Fixing Doxygen for libhydra.

Doxyfile.in

@@ -528,6 +528,7 @@ WARN_LOGFILE           =
 # with spaces.
 
 INPUT                  = @SRC_DIR@/src/libstrongswan \
+                         @SRC_DIR@/src/libhydra \
                          @SRC_DIR@/src/libcharon \
                          @SRC_DIR@/src/libsimaka \
                          @SRC_DIR@/src/libfast \

src/libhydra/hydra.h

@@ -16,11 +16,11 @@
 /**
  * @defgroup libhydra libhydra
  *
- */
-
-/**
- * @defgroup hydra hydra
- * @{ @ingroup libhydra
+ * @defgroup hplugins plugins
+ * @ingroup libhydra
+ *
+ * @addtogroup libhydra
+ * @{
  */
 
 #ifndef HYDRA_H_

src/libhydra/plugins/attr_sql/attr_sql_plugin.h

@@ -15,7 +15,7 @@
 
 /**
  * @defgroup attr_sql attr_sql
- * @ingroup plugins
+ * @ingroup hplugins
  *
  * @defgroup sql_plugin sql_plugin
  * @{ @ingroup attr_sql